1.5 A 280 kHz/560 kHz Boost Regulators# Technical Documentation: CS5173EDR8G Step-Up (Boost) DC-DC Converter
Manufacturer: ON Semiconductor
Component: CS5173EDR8G
Type: 1.5 A, 280 kHz, Step-Up (Boost) DC-DC Converter with Internal Power Switch
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## 1. Application Scenarios
### Typical Use Cases
The CS5173EDR8G is a monolithic, current-mode, step-up (boost) switching regulator designed to efficiently generate a higher DC output voltage from a lower input source. Its integrated 1.5 A, 40 V NPN power switch simplifies design and reduces external component count.
Primary Use Cases Include:
* Battery-Powered Systems: Extending usable voltage range from single or dual-cell Alkaline/NiMH (1.8V-3.0V) or single-cell Li-Ion (2.5V-4.2V) batteries to standard logic levels (3.3V, 5V, 12V).
* LED Driver Applications: Providing constant current or voltage for driving single or multiple series-connected LEDs in backlighting, indicators, or flashlights.
* Pre-Regulation: Generating an intermediate voltage rail (e.g., 5V or 12V) from a low-voltage main supply (e.g., 3.3V) to power other subsystems or ICs.
* Automotive Aftermarket Electronics: Powering sensors, displays, or modules from a vehicle's nominal 12V system, requiring stable output despite large input transients (load dump, cranking).
### Industry Applications
* Consumer Electronics: Portable audio players, digital cameras, handheld gaming devices, and e-readers.
* Industrial Controls: Sensor interfaces, loop-powered transmitters, and portable measurement equipment requiring stable voltage from variable sources.
* Telecommunications: Powering RF modules or interface circuits from a backplane or battery.
* Automotive: Interior lighting, infotainment systems (non-critical), and aftermarket accessory power supplies.
### Practical Advantages and Limitations
Advantages:
* High Integration: Internal power switch, oscillator, and control logic minimize board space and BOM.
* Wide Input Range: Operates from 2.7V to 30V, accommodating diverse power sources.
* Adjustable Output: Can be configured for outputs up to 35V using an external resistor divider.
* Fixed Frequency Operation: 280 kHz switching frequency allows the use of small, cost-effective inductors and capacitors, and eases EMI filtering.
* Key Protection Features: Includes cycle-by-cycle current limiting (peak switch current) and thermal shutdown for robust operation.
* Low Shutdown Current: Typically 80 µA when disabled, conserving battery life.
Limitations:
* Peak Current Limit: The internal switch is rated for 1.5 A peak. This limits maximum achievable output power, especially at very low input voltages where input current is high. Design must respect this limit.
* Non-Synchronous Topology: Uses an external Schottky diode for the freewheeling path. This introduces a diode forward voltage loss, reducing efficiency compared to synchronous boost converters, especially at low output voltages.
* Fixed Frequency: While beneficial for filtering, it does not allow frequency dithering for EMI reduction or variable frequency operation for light-load efficiency optimization.
* Output Disconnect: The output is not isolated from the input when disabled (shutdown), as the input is connected to the output via the inductor and catch diode.
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## 2. Design Considerations
### Common Design Pitfalls and Solutions
1. Pitfall: Inductor Saturation.
* Cause: Selecting an inductor with a
